This invention relates to display apparatus for use in a recording/playback device and, more particularly, to such apparatus for providing a cursor display as well as a display of the relative locations of cue signals recorded on the record medium with which the device operates.
In recording/playback devices that are particularly useful for the recording of dictated information and for the transcribing of same, it is advantageous to provide an indication of the present position of the record medium, relative to a reference location, and also to provide indications of the relative locations of signals representing the ends of "letters", or the locations of "instructions" and the like. Typically, an indication of the present position of the record medium has been provided, in accordance with prior art devices, by a mechanical pointing arrangement which is driven in synchronism with the record medium and which includes a mechanical indicator that scans an index scale. The index scale generally includes demarcations representing time-related quantities, such as minutes, and the relative location of the indicator designates the amount of record medium which has been consumed or which remains available.
In such dictation equipment, the index scale typically is a paper strip which is marked to indicate the ends of letters or the locations of special instructions which may be dictated by the user. Suitable solenoid-activated scribing instruments, heater elements, or the like are employed to be triggered by remotely controlled switches, usually provided on the dictation handset, to provide such marks.
These prior art arrangements, although satisfactory to carry out their intended purpose, suffer from various disadvantages. For example, the construction and assembly of a mechanical pointing arrangement is quite expensive and time-consuming. It is preferred, therefore, to replace this mechanical pointing arrangement with an electronic cursor indication.
Another disadvantage is that the use of a marked slip generally must accompany the dictated record medium and must be disposed in a compatible transcribing machine to enable the transcriptionist to observe the relative locations of "letter" and "instruction" marks. Of course, this information is lost if the marked index slip is misplaced or otherwise becomes separated from the dictated record medium. Furthermore, a separate index slip must be prepared by the user for each new record medium (e.g. each magnetic tape cassette, magnetic belt, magnetic disc, or the like) that he uses.
The aforenoted disadvantages have been overcome by the introduction of so-called electronic indicators which provide suitable displays of "instruction" marks. One type of electronic indicating system is disclosed in U.S. Pat. No. 4,051,540. In the patented system, an array of light indicating elements, such as light emitting diodes (LED's), liquid crystal devices (LCD's) or the like are selectively energized to provide visual indications of the locations of instruction signals recorded on the record medium. A so-called cue signal is recorded on the medium by the user of the apparatus to indicate the location of a particular instruction. In addition to recording the cue signal, the light indicating element which corresponds to the present position of the record medium is energized. Thus, the user is provided with a display of the locations of his recorded instructions. Prior to transcribing the dictated information, a transcribing machine is operated in a so-called "scan" mode, whereby each recorded cue signal is detected, and the relative location of that cue signal is indicated by energizing a corresponding light indicating element on the transcribing machine. However, in this patented system, a mechanical pointing arrangement is used to provide an indication of present position along the record medium.
An improved display apparatus is disclosed in U.S. Pat. No. 4,200,893. In this improved system, a micro-processor is used to control an array of light indicating elements to provide, in addition to "letter" or "instruction" displays, a cursor indication of the present position of the record medium. Thus, the mechanical pointing arrangement has been replaced by an electronic display arrangement.
In the electronic display arrangement described in the aforementioned patent, each light indicating element is associated with a time-related quantity. For example, each element is associated with a "minute" of recording time. A representation of recording time is provided by generating pulses in synchronism with the movement of the record medium. Such pulses are counted, and the count is used as a representation of recording time. However, and as mentioned above, if the record medium is a magnetic tape transported between a supply reel and a take-up reel, then the rate at which such pulses are generated varies as a function of the amount of tape remaining on the supply reel. Thus, a non-linear relationship exists between the count and the quantity of tape which has been transported (or which is available for use). To account for this non-linear relationship, the spacing between adjacent light indicating elements varies in a non-linear manner. For example, the spacing between adjacent elements in the range of 0 to 5 minutes is almost twice the spacing between adjacent elements in the range 25 to 30 minutes.
It is desirable to provide an array of light indicating elements which exhibit uniform spacing throughout the entire range. For such uniformly spaced elements to provide an accurate time-related indication of the quantity of record medium which has been consumed or which is available for use, the pulses which are generated in synchronism with the movement of the medium should be counted in a linear manner.